FOX HILLS AND LOWER MEDICINE BOW 33 



and pakcohotanic evidcncc to indicate essential contemporancity between the 

 Laramic formation of tlie Denver basin and at least the lower third of the Medicine 

 Bow formation. 



Lance flora — Table 4 shows that there are 26 species in common between the 

 Lance flora and that of the lower Medicine Bow formation. This is almost as 

 great a similarity as between thc Laramie and the Mcdicine Bow fiora. Moreover, 

 this similarit}' must by simple mathematical dcduction lcad to the conclusion that 

 the Lance and Laramie floras are more nearly contcmporaneous than has ever 

 previously been admitted. Knowlton maintained that the Lance flora was dis- 

 tinctly youngcr than that of the Laramic/ although he admittcd that the Lance 

 flora had not at that time bccn adequately describcd and that thcre was considcr- 

 able uncertainty attached to some of the localities from which Lance plants had 

 been collected. In an attempt to remedy both of thcse situations I have begun a 

 detailed field and laboratory study of thc Lance flora, which to date has yielded 

 the following preliminary observations : (1) Of the 58 rccordcd localitics ^ of reputed 

 Lancc plants, 14 localitics are definitely at horizons in thc Fort Union formation, 

 8 are definitely and 7 probably in the TuIIock or Ludlow membcr of the Lance, 

 11 are definitely and 9 probably in the Hell Creek member of the Lance, 1 is defi- 

 nitely in the Colgate member of the Fox Hills sandstone, and the remaining 8 

 localities are of very doubtful stratigraphic or gcographic position; (2) the list of 

 Lance plant species publishcd by Knowlton in 1919 ^ was at that date ncither 

 complete nor reliable, and must be completely revised to be of scientific value; 

 (3) the trcatment of the Lance flora as a single unit flora will lead to further con- 

 fusion; pending a more thorough invcstigation, it is apparent even in a preliminary 

 enumeration of species that the flora of the HcII Creek member of the Lance is 

 more closely allicd to that of the Laramie, Medicine Bow, Colgate, etc, of the 

 latest Cretaceous, whereas the floras of the TuIIock and Ludlow members of the 

 Lance are of Fort Union (Paleoccne) facies; (4) the only thoroughly reliable infor- 

 mation regarding the Lance flora is that of Berry * and Brown ^ on floras from the 

 Hell Creck mcmbcr; ncithcr of these floras includes elemcnts of Fort Union aspect. 



Despite the confuscd state of the Lance flora, it has been possible to show a 

 close relationship between the lower Medicine Bow flora and that of the Lance, 

 mainly from the coUcctions of Brown and Berry at the U. S. National Museiun, 

 and from my own collcctions at Princeton Univcrsity. AU of thcsc collcctions are 

 from the lower or Hell Creek member of the Lance, suggesting esscntial contem- 

 poraneity between the lower Lance, lower Medicine Bow, and Laramie formations. 

 Here is convincing corroboration of our basic assumptions, since the lower Lance, 

 Uke the Laramie and the lower Medicine Bow, is conformably just above the Fox 



' Knowlton. F. H., op. cit.. 104. 



» Stanton, T. W., and Knowlton, F. H., Bull. Geol. Soc. Am., vol. 8, 127-156, 1897; Leonard, A. G., U. S. Geol. Survey 

 BuU. 316, 201, 202, 1907; Knowlton, F. H., Washington Acad. Sci. Proc, vol. 11, 179-238, 1909; Knowlton, F. H., Jour. Geol., 

 vol. 19, 369-371, 1911; Calvert, W, R,, U. S. Geol. Survey BuII. 471-D, 195, 198, 1912; Winchester, D. E., Hares, C. J., 

 Lloyd, E. R., and Parks, E, M., idem, BuII, 627, 24, 25, 1916; Rogers, G. S., and Lee, W., idem, BuII. 749, 29, 34, 1923; 

 Hewett, D. F., idem, Prof. Paper 145, 27-35, 1926; Hares, C, J., idem, BuII. 775, 29, 1928; Dobbin, C. E., idem, BuII. 812-A, 

 11, 1929; Berry, E. W., idem, Prof. Paper 185-F, 127-132. 1934; Pierce, W. G., idem, BuII. 847-B. 56, 1936. 



'Knowlton, F. H., U. S. Geol. Survey BuU. 696, 764, 1919. 



* Berry, E. W., U. S. Geol. Survey Prof. Paper 185-F, 1934. 



'Brown, R. 'W'., U, S. Geol. Survey Prof. Paper (Manuscript, 1937). 



